Casting apparatus



Sept 17, 1940. I E ROY v. CLARK CASTVING APPARATUS Original Filed Dec. 22, 1938 l5 Sheets-Sheet l Sept 17, 1940. LE ROY v. CLARK CASTING' APPARATUS Original Filed Dec.

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CASTING APPARATUS Original Filed Dec. 2 2, 1938 13 Sheets-Sheet l? VENTM? fgov V @LAQK Patented Sept. 17, 1940 PATENT OFFICE CASTING APPARATUS Le Roy V. Clark, Latrobe, Pa., assignor to American Cyallamid & Chemical Corporation, New York, N. Y., a corporation of Delaware n Original application December 22, 1938, SerialNo. 247,144. Divided and this application August 5,

1939, Serial No. 288,519

6 claims. (01.140471) This application is a division of application No. I.247,144 led December 22, 1938. The present invention relates tov an apparatus 'for castingr vplugs about lead wires, such plugs being` useful in the manufacture of electricblast- .ing lnitiators. In this art, an electric blasting initiator usuall includes a thin metal open-ended shell into which Vis Afilledzdetonating or explosive charge of Varied compositions. This rst, or base, chargeis usualxlyset off under the influence of a small quantity :of explosive of the primary initiating type such as lead azide, mercury fulminate or the like in uthe manner well known to those skilled in the art. The primary initiating explosive may be set .oiby .the iniluence of a small gauge electrically .heated bridge wire embedded therein, and extendying between the ends of a pair of lead wires, the y.latter 4being held in a plug of asphaltic or other v'composition inserted in the upper end of the shell. The plug'is usually topped with thermoplastic materials such as pitch and sulfur to hold ,.the parts together in a waterproof seal. When l.the two lead orleg wires are attachedto a suitablesource of E. M. F., the bridge wire is heated ,toincand'escenca exploding the primaryl ignition composition in which it is embedded, which latter initiates detonation in the base charge. It is clear from the above description that the bridge wire extending between the ends of the leg wires .must .be .positioned below the baseof the plug and in an` exposed position to facilitate embedding it into the primary initiating explosive. Because ,of the. exposedor open position of the bridge wire, this type of plug is commonly referred to yas the' open bridge wire type. .For` reasons well known-to those skilled in the .,art,'it is often'desirable from technical or other reasons, to employ an ignition'head capable of delivering a small spit of hot llame to impinge .across a short space against an explosive composition, or, for example, to impinge against and ignite, the delay powder train in delay electric blasting caps. For this purpose, it is undesirable and impracticable to have an exposed bridge wire embedded in loose powder as described above. v*'Ivhe desired result has been accomplished y.vforyears past by use of an ignition plug of the general design of that shown in Fig. 21, in which the bridge lwire between the ends of the leg wires is recessed into a small cavity in the base of the plug. `The cavity is then Vfilled with the desired powder composition, `in the form of a thick paste with a. solution of any suitable type ofv binder involatilesolvent. Thisntype of plug (Fig. 21)

'was accomplished in a special type of mold in therefore is commonly spoken of as the pasted type.

Manufacture of pasted typeplugs has always presented great technical difliculties. For instance, years of effort in this direction have failed 5 to produce any practicable way of aflixing the bridge wire to the leg wires. after formation of the cavity in the base of the plug. Heretofore the only known method for the manufacture of these plugs involved the following operations:

It has been the practice to place a small plug of thermoplastic material around, andy a short distance back of the ends of the leg wires to iirmly'hold them in position. The assembly .was then taken to the soldering operation and the '15 bridge wire attached. Following this step, the assembly was sent to a second castingoperation `for completion of the plug and formation of the cavity around the bridge wire. This latter step 2O which the thermoplastic plug composition was poured around the small original plug to form va completed plug in outward appearance resembling that shown in Fig. 21. A plug prepared as just described is referred to as a double-cast, pasted type.

- Much trouble has been experienced with such construction in that it is difficult to obtain an integral joint between the plug material initially and finally cast, and in the assembly operation involving handling of these plugs they are frequently broken at the joint between castings, or the plug is found to be useless by virtue of the bridge wire having been covered during the sec- `avoiding the objections heretofore existing.

Inasmuch as a blasting initiator and its parts are. of small size, they are diicultly handleable. Moreover, due to the fact that failures must be eliminated to a maximum extent, it is necessary ythat these devices be manufactured with extreme precision. Consequently, it is another important yobject of this invention to design a machine for -handling these small parts with precision in large quantities and to, as far as possible, eliminate inaccuracies due to individual handling. v To this end, the invention includes the novel Y arrangement, combinationl and construction lof parts more fully described hereinafter and shown in the accompanying drawings, in which- Fig. l is a top plan view of a device embodying the present invention;

Fig. 2 is a side elevation thereof;

Fig. 3 is a transverse sectional view taken along the line 3-3 of Fig. l, showing the attachment of the lead wire clamping device;

Fig. 4 is a similar View with the parts in an advanced position and showing the threading of the lead Wires;

Fig. 4a is a plan view of the wire clamp in open position;

Fig. 5 is a similar view of the parts farther advanced, showing the wires at the beginning of the cutting operation;

Fig. 6 is a sectional View along the line 3 6 of Fig. 5 showingvthe wire cutter, the wires being shown in dotted lines;

Fig. 7 is a similar view with the cutter in full return position showing the wires in advanced position in dotted lines;

Fig. 8 is an enlarged detail view showing the manner of attaching the bridge wire to the lead wires;

Fig. 9 is a similar view showing completed pairs of lead wires with bridges attached;

Fig. 10 is a top plan view of the casting mech-1 anism;

Fig. 11 is a front elevation thereof;

Fig. 12 is a rear View of the same device;

Fig. 13 is a perspective view of the lower jaw member;

Fig. 14 is a perspective of the positioning comb;

Fig.. 15 is a transverse sectional View along the line I5-l5 of Fig. l2;

Fig. 16 is a view similar to Fig. 15 with the parts in an advanced position and showing the manner of detachment of the positioning comb;

Fig. 16a is a detail View showing the manner of removal of the moving parts from the cast plug after solidication;

Fig. 17 is a similar view with the parts farther advanced to the casting position;

Fig. 18 is an enlarged detail of a part of Fig. 1'7 showing the manner of gripping the lead wires during the casting operation;

Fig. 19 is a sectional view along the line IQ-IB of Fig. 18;

Fig, 20 is a plan View of the bar 8l showing the relationship of the lead wires and a lip 88';

Fig. 21 is a perspective of the completed single cast plug; and

Fig. 22 is a sectional view of a typical electric blasting initiator showing the single cast plug in place.

Wire threading, cutting, and advancing operation The mechanism for performing these operations is shown in Figs. 1 to 5 and may consist of a base plate I suitably secured to a table 2, the former carrying bifurcated arms 3 extending upwardly and carrying between their terminal portionsthe assembly about to be described. The arms 3 are preferably provided with a turn-table section 5, mounted upon a corresponding part of the base plate I and secured thereto as by bolt 6. Thus the mechanism is mounted for rotation about the central point t for convenience.

A bed plate l, L-shaped in cross section, is carried at itsl ends between the upper portions of the arms 3 by cap screws 8, so that the plate andthe mechanism carried thereby may be oscillated about the screws as a center. The ends of the bed plate l are provided with lugs 9 between which is carried shaft I0. On this shaft is xedly mounted cam arm II having a roller I2 at the end thereof, and also a pair of pressure fingers i3. The sides of the cam arm II are held between a roller I4 mounted on the end of that they may be cut and advanced -a sufficient amount to permit `attachment of the bridge wire in any suitable manner, such as by soldering, swaging or welding, a body member substantially V-shaped in cross section and indicated generally at 29 is provided, having a clamp 2| pivoted as at 22. The surface 23 is adapted to rest upon the bed plate l, whereas the other surface 24 is arranged to support the Wires. The body member 23 is provided with plates 25 and 26 at each longitudinal edge thereof, the upper edges of which terminate in a series of teeth 2l and 28 respectively.

When the wire clamping mechanism is moved in the direction of the arrows from the position. shown in Fig. 3 to the position shown in Fig. 4, the surface 23 rests in proximity to the bed plate 'i'. The bed plate and its mechanism and the clamping device and its mechanism is then oscillated in a counterclockwise direction about the common pivot 8 until the roller I on the arcuate the bed plate 7 and an extension bar 3l. lThis bar is secured to the bed plate I by means of rods 32 (Fig. 1) passing through the bed plate 'I and terminating in a connecting member 33 with springs 3f! between the connecting member 33 and the extension bar 3|. The extension bar 3l is thus normally held away from the bed plate I by the springs. Under the action of cam 39, however, the extension bar 3l may be drawn tightly up against bed plate l, thus making holes 30 available for threading the wires. The ends of the wires 23, after passing through these holes 33, are turned down as at 35 (Fig. 4) to tempo'- rarily hold them in this position and the main part of each wire is then positioned between the teeth 2l and 23 and against the surface 24. When all of the series of wires are thus located, the clamp 2l is thenbrought down against the wires to Ahold them in that position, hook 36 .at the end of the clamping arm (Fig. 4a) engaging in notch 3'! on the underside of the body member 20 and cammed tight by means of leverr38. The wires are thus held in spaced relationship ready for the next operation, whichis the cutting Step.

The parts are then further oscillated in a counterclockwise direction to occupy the position shown in Fig. 5. At this point, it is to-"be noted that cam arm H rests against stop 40 on It will be noted that-the bea'piateris -prolon the bed plate 1. lshow that as the slide 46 under impulse of the plate. The cutter blade 44 is suitably mounted on the carriage 43 in line with the projecting ends of the wires 29 (Fig 1). Movement of the carriage 43 in a direction toward the observer in Fig. or in the direction of the full line arrow in Fig. 6, causes the ends of the projecting wires to be snipped olf flush with the surface of the bed plate 1 and extension bar 3|. After rthe wires are all cut off, the carriage 43 is then returnedin the opposite direction and to its initial position. Fig. 1 shows the carriage near the end of its extreme leftV hand or initial positon. Further movement to the left causes the carrage to engage trip 45 (Fig. 6), which is carried by a slide 46, which is, in turn, mounted Reference to Fig. 6 will carriage 43, is moved to the left within the depression in the underface of body member 2U,

the end of the slide moves into a guiding recess 41 until the body member 2|] of the wire clamping assembly clears the corners 48 and 49 of the slide. At this point, vunder the action of the pressure fingers I3, the body member is moved toward' the bed plate 1, the thickness of the slide 46 and consequently, thewires held by the clamping assembly are advanced through the holes 36 between the bed plate and extension bar by that amount. They are now ready to have the bridgewires soldered in position.

Soldering the bridge wires Referring now to Figs. 7 and 8, which show the wires advanced an equal distance beyond the bed plate and the extension bar, bridge wires are now soldered in place between adjacent pairs of lead wires in the following manner:

One end of a spool of small gauge wire, usually of platinum or a platinum alloy, is placed adjacent the top of the extreme right hand wire indicated at 56 and a drop of solder applied Aotherwise removed so as to leave pairs of lead wires, each connected by a section 5I of a bridge wire. f

The bed plate and the wire clamping mechanism along with the lead wires held thereby is .then oscillated in a clockwise direction back to Reference is here made particularly to Figs. 11, 12 and 13, in which the casting mechanism is generally illustrated. This assembly consists of a supporting element 52 having upwardly `vided with a dovetail 42 engaging a cutter carriage 43 which slides longitudinally on the bed positioned between vertical lugs 18.

projecting arms'53 carrying, by means of pivot screws 54, end plates 55 to which is attached the lowersection of a jaw member 56. Anchored in the lower jaw member 56 are vertical rods 51 which pass loosely through and hold thereon in parallelism an upper jaw member 58. The tops of the vertical rods 51 are attached to cross bar 59.

- Auxiliary rods 65 extending between the upper and lower jaw members carry springs 6l normally exerting against the jaw members and tending'to separate them. A cam lever .62 is pivotally mounted on cross bar 59 and serves to exert pressure upon the bearing plate 63 mounted upon the upper jaw member 58 and move it downwardly towards the lower jaw memberv 56 against the action of springs 6l.

The lower jaw member 56 is provided with a pair of integral extensions 64 carrying between them rock shaft 65 which carries a pair of retaining devices 66 and a` projection 61 which terminates-in a roller 66. This roller is adapted to ride against the curved arm 69 pivoted as at v16 to the base 52. A spring 1l extends between the other or free end of the curved arm 69 and the base 52.

Referring to Figs. l l and i4, there is shown a positioning comb comprising av frame 12 having end channels 13, downwardly extending teeth 14 and handles 15. i

Referring back to Fig. 11 and with the upper and lower jaw members 58 and 56 in the position there shown in full lines, the comb of Fig. `lll is inserted between upper and lower jaws 58 and 56 so that the channels 13 straddle rods 51. The lever 62 is then moved slightly (dotted lines Fig. 11) to cam the jaw 58 against the top of the comb sufficiently to temporarily hold the parts in this position.

The body member Z6 with the lead wires' clamped therein is then attached to the casting mechanism as shown in Fig. l5 by movement in the direction of the arrows until the edge 16 of the body rests'upon the top of horizontal ledge 'E1 (Figs. 13 and 16) the ends of the body being During this movement, each pair of lead wires with its attached bridge wire falls between the teeth 14 on the comb. When thus positioned, the handle "I9 is grasped and moved in a clockwise direction (Fig. which causes the assembly to oscillate in that direction until the roller 66 rides into the depression 86 in the curved arm (Fig. 16). During thisl movement, pressure finger 66 is caused to move about its shaft 65 until the fingers bear upon the inside V of the body 26 of the wire clamping device and thus hold it in the'position shown in Fig. 16. v n

Referring now to Figs. 10, l2, 15 and 16, lugs 83, which are cast integral with end plates 55, carry between them shaft 64 on the ends of which are mounted crank arm 55. To the end of this arm is p-ivoted as at 66 a bar 8l having a series of lips 83 projecting therefrom. As shown in Fig. l5, the bar Slcannot move in a clockwise direction by reason 'of the fact that its extension 86 bears against shoulder 96 on the arm 65. It can, however, 4move slightly in a counterclockwise direction and against the spring 9i.

The above parts are now moved in the direction of the arrow in Fig, 15 by the handle 92 and into the position shown in Fig. 16. At this point, the lips 68 together with lips 93 on the member 94 hold firmly between them the ends of the lead wires with the bridge wires attached as shown in Figs. 18, 19 and 20. This relationship is important in the actual casting operation which will be described more fully hereinafter. The cam lever 62 is then backed oif which permits the upper jaw 58 to move upwardly a slight distance and thus remove the comb 12.

The lever handle 62 is now moved in a counterclockwise direction (Fig. 12) until it occupies the position shown in the dotted lines. At this point, the lower edge 8| of the bearing plate 63 bears upon the upper edge of the bar 81 and locks the latter securely in position. At this time, they upper jaw 58 hasl been brought into approximation with the lower jaw 56 as shown in Fig. 17. Reference to Figs. 18 and 19 will show that the upper and lower jaws are provided with substantially semi-cylindrical grooves therein which, when the two jaws are brought together, form a cylindrical cavity in each of which is substantially centrally located a pair of lead wires with the bridge wires attached. The walls of this cylindrical cavity define a mold within which the material for the eventual plug is cast, the ends' of the lead wires with its bridge wire being protected by the lips 88 and 93.

The parts are now further oscillated in a clockwise direction as shown in Fig. 17 until the roller 58 engages the groove 95. At this point, the mold cavity is substantially vertical. A suitable insulating composition such as an asphaltic composition, either with or without diluents and fillers, such as mica, in a more or less fluid condition is then poured from the ladle 96 into each of the mold cavities. Any other thermoplastic insulating material may be used in place of the above. As a matter of fact, it is preferred thatsuch a composition be chosen from those which are noninflammable and incombustible, which, however, have the charactertistics of good adhesion, insulating qualities and being substantially unshrinkable at low temperatures. The halogenated hydrocarbons are eminently satisfactory for this purpose. Upon solidification, thisI fluid insulating material forms a one piece plug within which the lead wires are securely embedded.

Upon solidication of the plug material, the parts are then oscillated counterclockwise to the position shown in Fig. 16. At this point the lever 62 serves to relieve the pressure between the edge 8| of the bearing plate and the upper surface of the bar 81 while release of the lever 92, by camming the lower end thereof against lug 82, moves bar 81 away from upper jaw 58. To facilitate movement of the bar 81 away from the cast plug, a pair of upstanding tapered projections 91 (Figs. 10 and 15) are formed on the upper edge of the member Sli, which are adapted to engage with similarly formed recesses 98 in the bar 81. Conjsequently, as the handle 92 is moved to a releasing position, the bar 81 rides upon the tapered projections 91 and thus moves away from the cast plug in a slightly upward as well as outward direction. Ihe fact that all moving parts are backed away in an upward direction prevents mutilation or breaking of the bridge wire and the fragile material of which the plug is made.

At 'this point.' the Wire clamping assemblyis still in position. Further oscillation in a counterclockwise directionV releases the pressure fingers 66 from the clamping assembly and the latter is then removed. Release of the lever 38 and clamping arm 2| now frees the pairs of lead Wir-es with the plugs cast around the ends thereofv for further disposal as desired.

A completed single cast plug is shown at in Fig. 21.

A typical electric blasting initiator assembly is shown in Fig. 22 to include a thin shell of metal |0| containing any suitable explosive or detonator composition |02 with a single cast plug |00 having a pasted ignition composition |03 within which bridge wire I is embedded. A llV |04 of any suitable thermoplastic material, either similar or dissimilar to the plug material, overlays the top of the plug |00 and not only surrounds the ends of the insulation on the lead Wires and prevents the same' from back ravelling, but also securely xes the plug within the shell. Where desir-ed, an assisting crimp |05 may be used.

While the invention has been shown and described with specific reference to particular embodiments, it is to be understood that it is not to' be limited thereto but is to be construed broadly and restricted only by the scope of the appended claims.

I claim: l l

l. Mechanism for securing bridge Wires between the ends of lead wires in electric blasting initiators including a body member having at one edge thereof a series of teeth, a swinging clamp element secured to the body member and capable of holding wires between it and the body member, an apertured device in proximity to the teeth, the apertures and th-e teeth being spaced apart substantially the same distance.

2. The mechanism of claim 1 in which means are provided to space the body member and its teeth from the apertured device.

3. The mechanism of claim 1 in which means are provided to space the body member and its teeth from the apertured device with means to move the body member and teeth toward the apertured device a predetermined distance. I

4. The mechanism of claim 1 in which the apertured device comprises two members capable of being brought together to form apertures therebetween.

5. The mechanism of claim 1 with a cutter carried by a slide mounted on the apertured device, the cutter being movable successively over the apertures.

6. The mechanism of claim 1 with a cutter carried by a slide mounted on the apertured device, the cutter being movable successively over the apertures, said body member and teeth'being spaced from the apertured device and means operated by the slide for advancing the body member and teeth toward the apertured device.

LE nov v. CLARK. 

